To evaluate the clinical effect of 3D printing guided total knee arthroplasty (TKA) using subvastus approach.

We retrospectively reviewed 63 osteoarthritis patients who underwent 3D printing guided by subvastus approach in our department between March 2015 and March 2016. Visual analogue scale, knee function score and patella Feller score were assessed before and 3 months after surgery. Patients' quadriceps muscle strength and knee joint activity were assessed preoperatively, 3 months and 6 months postoperatively. The Q angle of extension and its patella extrapolated Q angle, 30° Q angle of flexion and its patella extrapolation Q angle were measured preoperatively and 1 month postoperatively.

All patients were successfully followed up for 12-18 months with an average of 14.5 ±2.7 months. The postopeartive VAS score (1.8±0.4), HSS score (93±6) and patella Feller score (26±4) were significantly different than the preoperative data (6.8±2.2、37±6、16±6) (t=18.223, t=-51.741, t=-11.485, P<0.05). Muscle strength (80±8) was significantly improved compared with preoperative (74±8) data, difference was statistically significant (F=20.771, P<0.05). The range of knee flexion and extension activities at 3 months postoperatively was statistically improved (F=306.062, F=105.050, P<0.05). The extension angle and 30° Q angle of flexion and its patella extraverted Q angle were significantly improved compared with those preoperatively, differences were statistically significant (extension position: t=20.489, t=6.753, t=4.891, flexion: t=21.497, t= 2.853, t=5.698, P<0.05).

The application of the 3D printing guided total knee arthroplasty with subvastus approach is effective, with fewer complications and less trauma.